1. Field of the Invention
This invention relates to an improved mechanical interlock for multiple switch-type circuit breakers mounted in linear alignment, allowing easy access and replacement of individual circuit breakers, while mechanically limiting the circuit breaker so that only one, or a predetermined number of, breaker switches, can be in a selected position at a time and which cannot be dismantled with ordinary hand tools.
2. Description of the Related Art
It is common to restrict circuit breakers to limit movement, particularly, to prevent unintended operation of one or more of the individual breakers. Limitation of breakers is very desirable in situations where multiple power sources are present to power a limited number of energy consuming devices.
Previously, numerous devices have been utilized to electronically or mechanically limit circuit breakers. Some of these devices are designed to be used with existing circuit breaker boxes commonly found in residential and commercial settings. One such example can be found in U.S. Pat. No. 5,393,942 to Reiner et. al. The Reiner patent discloses an after-market product which is mechanically fixed to existing circuit breakers and provides a padlock hasp for securing the device and limiting tampering or unintentional tripping of the breaker switches. The Reiner device and similar devices have the inherent problem of difficult and unwieldy installation and operation. Moreover, the use of padlocks or other limiting locks, prevents quick and easy manipulation of the breakers when desired and requires only ordinary hand tools to alter the position of the device between circuit breaker switches, or to remove the switches.
Another mechanical interlock device is described in U.S. Pat. No. 3,705,280 to Harms. The device disclosed is particularly suited to a pair of opposed breaker switches so that by switching one breaker ON, the second switch is mechanically forced into the OFF position. The obvious drawback to this device is that it is not readily adaptable to an odd number of switches in a series. Further, it does not allow all switches present to be in the OFF position, which may be desirable for maintenance or repair work on the circuit breaker, the powered device, or structure. Many other devices useful for mechanically limiting pairs of circuit breakers are available and are disclosed in U.S. Pat. No. 4,516,100 to Wallace et al., U.S. Pat. No. 5,725,085 to Seymour et al. and U.S. Pat. No. 4,902,859 to Witzmann et al. However, each of these patents disclose devices which are complex or difficult to operate and maintain.
Other devices useful for limiting the actuation of more than one circuit breaker at a time have been disclosed. One such device is U.S. Pat. No. 3,801,758 to Shand et al. The Shand device uses individual covers mounted over each circuit breaker switch and slidable along a pair of opposed guide rods. One less cover than the number of breaker switches present is provided so that only one breaker switch is exposed and accessible at a time. This device requires installation of multiple parts, including the individual breaker switch covers and the guide rods. A difficulty arises when one or more of the circuit breakers has to be removed in that the guide rods, and the attached covers, have to be removed in order to access the breaker switches. Therefore, during the installation of new switches or the removal of existing switches, it is possible to inadvertently trip adjacent switches. This can result in the overloading of switches, damaged switches or powered devices or systems operatively associated with the circuit breakers.
What is needed is a mechanical interlock device which effectively limits a series of breaker switches so that a predetermined number of adjacent switches will be in the desired ON or OFF position at one time. The instant invention improves upon related devices known within the industry by providing a novel design which easily and effectively mechanically limits the number of circuit breakers in linear alignment so that predetermined number of adjacent switches will be in the desired ON or OFF position at one time. The apparatus disclosed herein is intended to be used when only one switch in a series of switches, in linear alignment, is to be in the ON position at a time. However, the device works equally well in situations where all but one switch is desired to be in the ON position or for any series of switches in linear alignment where it is desired that adjacent switches be operable. For example, in a series of five switches in linear alignment where any two adjacent switches can be in the ON position with the remaining three switches in the OFF position, the apparatus will be configured to allow access and operation to two adjacent switches at a time. Therefore, switches one and two, two and three, three and four, or four and five will be operable with the remaining three mechanically "locked" into the OFF position. Further, the apparatus of the present invention can be reconfigured and utilized without changing the same basic apparatus design for any number of breakers switches in linear alignment and to limit any number of the present breaker switches.